ares_init.c

/* $Id$ */

/* Copyright 1998 by the Massachusetts Institute of Technology.
 *
 * Permission to use, copy, modify, and distribute this
 * software and its documentation for any purpose and without
 * fee is hereby granted, provided that the above copyright
 * notice appear in all copies and that both that copyright
 * notice and this permission notice appear in supporting
 * documentation, and that the name of M.I.T. not be used in
 * advertising or publicity pertaining to distribution of the
 * software without specific, written prior permission.
 * M.I.T. makes no representations about the suitability of
 * this software for any purpose.  It is provided "as is"
 * without express or implied warranty.
 */

#include "setup.h"
#include <sys/types.h>

#if defined(WIN32) && !defined(WATT32)
#include "nameser.h"
#include <iphlpapi.h>
#include <malloc.h>

#else
#include <sys/param.h>
#ifdef HAVE_SYS_TIME_H
#include <sys/time.h>
#endif

#ifdef HAVE_SYS_SOCKET_H
#include <sys/socket.h>
#endif

#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <arpa/nameser.h>
#ifdef HAVE_ARPA_NAMESER_COMPAT_H
#include <arpa/nameser_compat.h>
#endif
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#endif

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <time.h>
#include <errno.h>
#include "ares.h"
#include "ares_private.h"
#include "inet_net_pton.h"

#ifdef WATT32
#undef WIN32  /* Redefined in MingW/MSVC headers */
#endif

static int init_by_options(ares_channel channel, struct ares_options *options,
                           int optmask);
static int init_by_environment(ares_channel channel);
static int init_by_resolv_conf(ares_channel channel);
static int init_by_defaults(ares_channel channel);

static int config_nameserver(struct server_state **servers, int *nservers,
                             char *str);
static int set_search(ares_channel channel, const char *str);
static int set_options(ares_channel channel, const char *str);
static const char *try_option(const char *p, const char *q, const char *opt);
#ifndef WIN32
static int sortlist_alloc(struct apattern **sortlist, int *nsort, struct apattern *pat);
static int ip_addr(const char *s, int len, struct in_addr *addr);
static void natural_mask(struct apattern *pat);
static int config_domain(ares_channel channel, char *str);
static int config_lookup(ares_channel channel, const char *str,
                         const char *bindch, const char *filech);
static int config_sortlist(struct apattern **sortlist, int *nsort,
                           const char *str);
static char *try_config(char *s, const char *opt);
#endif

int ares_init(ares_channel *channelptr)
{
  return ares_init_options(channelptr, NULL, 0);
}

int ares_init_options(ares_channel *channelptr, struct ares_options *options,
                      int optmask)
{
  ares_channel channel;
  int i, status;
  struct server_state *server;
  struct timeval tv;

#ifdef CURLDEBUG
  const char *env = getenv("CARES_MEMDEBUG");

  if (env)
    curl_memdebug(env);
  env = getenv("CARES_MEMLIMIT");
  if (env)
    curl_memlimit(atoi(env));
#endif

  channel = malloc(sizeof(struct ares_channeldata));
  if (!channel)
    return ARES_ENOMEM;

  /* Set everything to distinguished values so we know they haven't
   * been set yet.
   */
  channel->flags = -1;
  channel->timeout = -1;
  channel->tries = -1;
  channel->ndots = -1;
  channel->udp_port = -1;
  channel->tcp_port = -1;
  channel->nservers = -1;
  channel->ndomains = -1;
  channel->nsort = -1;
  channel->lookups = NULL;
  channel->queries = NULL;
  channel->domains = NULL;
  channel->sortlist = NULL;
  channel->sock_state_cb = NULL;

  /* Initialize configuration by each of the four sources, from highest
   * precedence to lowest.
   */
  status = init_by_options(channel, options, optmask);
  if (status == ARES_SUCCESS)
    status = init_by_environment(channel);
  if (status == ARES_SUCCESS)
    status = init_by_resolv_conf(channel);
  if (status == ARES_SUCCESS)
    status = init_by_defaults(channel);
  if (status != ARES_SUCCESS)
    {
      /* Something failed; clean up memory we may have allocated. */
      if (channel->nservers != -1)
        free(channel->servers);
      if (channel->domains)
        {
          for (i = 0; i < channel->ndomains; i++)
            free(channel->domains[i]);
          free(channel->domains);
        }
      if (channel->sortlist)
        free(channel->sortlist);
      if(channel->lookups)
        free(channel->lookups);
      free(channel);
      return status;
    }

  /* Trim to one server if ARES_FLAG_PRIMARY is set. */
  if ((channel->flags & ARES_FLAG_PRIMARY) && channel->nservers > 1)
    channel->nservers = 1;

  /* Initialize server states. */
  for (i = 0; i < channel->nservers; i++)
    {
      server = &channel->servers[i];
      server->udp_socket = ARES_SOCKET_BAD;
      server->tcp_socket = ARES_SOCKET_BAD;
      server->tcp_lenbuf_pos = 0;
      server->tcp_buffer = NULL;
      server->qhead = NULL;
      server->qtail = NULL;
    }

  /* Choose a somewhat random query ID.  The main point is to avoid
   * collisions with stale queries.  An attacker trying to spoof a DNS
   * answer also has to guess the query ID, but it's only a 16-bit
   * field, so there's not much to be done about that.
   */
  gettimeofday(&tv, NULL);
  channel->next_id = (unsigned short)
    (tv.tv_sec ^ tv.tv_usec ^ getpid()) & 0xffff;

  channel->queries = NULL;

  *channelptr = channel;
  return ARES_SUCCESS;
}

static int init_by_options(ares_channel channel, struct ares_options *options,
                           int optmask)
{
  int i;

  /* Easy stuff. */
  if ((optmask & ARES_OPT_FLAGS) && channel->flags == -1)
    channel->flags = options->flags;
  if ((optmask & ARES_OPT_TIMEOUT) && channel->timeout == -1)
    channel->timeout = options->timeout;
  if ((optmask & ARES_OPT_TRIES) && channel->tries == -1)